… order.

1. `TestAttempt` events would wait for the `TargetCompleteEvent` to be posted before being posted.

2. There was an implicit requirement for the `TestAttempt` events to be posted in a specific order.

3. This didn't break in the noskymeld case because we fulfilled this ordering by using the order of performing the attempts themselves. The sequence would look like:
    + post `TargetCompleteEvent`
    -> perform attempt #1
    -> post `TestAttempt` #1
    -> perform attempt bazelbuild#2
    -> post `TestAttempt` bazelbuild#2

4. With skymeld, however, it could happen like this:

    + defer `TargetCompleteEvent` to wait for `CoverageActionFinishedEvent`
    + perform attempt #1 -> defer posting `TestAttempt` #1 & wait for `TargetCompleteEvent`
    + perform attempt bazelbuild#2 -> defer posting `TestAttempt` bazelbuild#2 & wait for `TargetCompleteEvent`
    + `CoverageActionFinishedEvent` -> release & post `TargetCompleteEvent`
    + `TargetCompleteEvent` -> release & post `TestAttempt` bazelbuild#2
    + `TargetCompleteEvent` -> release & post `TestAttempt` #1

Due to (2), the undefined ordering in (4) would cause an issue.

This CL fixes that by ensuring a FIFO ordering of the deferred events.

PiperOrigin-RevId: 572165337
Change-Id: Iac4d023d946865b8b81f15b119417192dc4b5c53